No Arabic abstract
Projective varieties with ample cotangent bundle satisfy many notions of hyperbolicity, and one goal of this paper is to discuss generalizations to quasi-projective varieties. A major hurdle is that the naive generalization fails, i.e. the log cotangent bundle is never ample. Instead, we define a notion called almost ample which roughly asks that the log cotangent is as positive as possible. We show that all subvarieties of a quasi-projective variety with almost ample log cotangent bundle are of log general type. In addition, if one assumes globally generated then we obtain that such varieties contain finitely many integral points. In another direction, we show that the Lang-Vojta conjecture implies the number of stably integral points on curves of log general type, and surfaces of log general type with almost ample log cotangent sheaf are uniformly bounded.
In this paper, we extend a uniformity result of Dimitrov-Gao-Habegger to dimension two and use it to get a uniform bound on the set of all quadratic points for non-hyperelliptic non-bielliptic curves in terms of the Mordell-Weil rank.
In this paper, we give an affirmative answer to a conjecture in the Minimal Model Program. We prove that log $Q$-Fano varieties of dim $n$ are rationally connected. We also study the behavior of the canonical bundles under projective morphisms.
We construct smooth projective varieties of general type with the smallest known volumes in high dimensions. Among other examples, we construct varieties of general type with many vanishing plurigenera, more than any polynomial function of the dimension. As part of the construction, we solve exactly an optimization problem about equidistribution on the unit circle in terms of the sawtooth (or signed fractional part) function. We also solve exactly the analogous optimization problem for the sine function. Equivalently, we determine the optimal inequality of the form $sum_{k=1}^m a_ksin kxleq 1$, in the sense that $sum_{k=1}^m a_k$ is maximal.
Let $X$ be a smooth projective surface and $Delta$ is a normal crossing curve on $X$ such that $K_X+Delta$ is big. We show that the minimal possible volume of the pair $(X, Delta)$ is $frac{1}{143}$ if its (log) geometric genus is positive. Based on this, we establish a Noether type inequality for stable log surfaces, be they normal or non-normal. In the other direction, we show that, if the volume of $(X, Delta)$ is less than $frac{1}{143}$ then $X$ must be a rational surface and the connected components of $Delta$ are trees of smooth rational curves.
We survey some recent work on the geometric Satake of p-adic groups and its applications to some arithmetic problems of Shimura varieties. We reformulate a few constructions appeared in the previous works more conceptually.